DC-DC conversion at Very High Frequencies - Challenges, progress and prospects

Electrical energy conversion systems are constantly improving, in line with the advances made by research in response to societal, industrial and/or military needs. Major breakthroughs have enabled the mass production of power converters capable of converting electricity from a variety of sources, over wide voltage/power/frequency ranges, to loads as diverse as each other. These include the invention of mercury vapor rectifiers at the beginning of the 20th century, the development of the bipolar transistor in the 1940s, the massive spread of MOSFETs (Metal Oxyde Semiconductor Field Effect Transistors) in the 1970s, and IGBTs (Insulated Gate Bipolar Transistors) in the 1990s, to name but a few notable examples.

Since the 1970s and the rise of power electronics, increasing power density and improving energy efficiency have been major areas of research in this field. This demand is all the more prevalent in today's context of massive electrification of energy systems (transport, machines, utilities, etc.).

A natural way to reduce the footprint of passive components within the converter is to increase the switching frequency, thereby reducing the amount of reactive energy to be stored during an operating cycle. Technological advances in power semiconductor components and the emergence of large-gap semiconductors now enable traditional high-efficiency power conversion applications at frequencies of up to a few MHz. However, a number of bottlenecks linked to conventional converter topologies and the component technologies used, which we will discuss, are holding back substantial gains in power density beyond these frequencies.

Could very-high-frequency power conversion be the start of a major new breakthrough in terms of integration and sustainability? At the frontier between power electronics and radio frequencies, it proposes to operate at very high switching frequencies (the 30-300 MHz frequency band), combining resonant topologies and adapted components. This is an emerging field, and there are many issues at stake. This article summarizes the issues and advances in the field, as well as the outlook for the future.

At the end of the article, readers will find a glossary and table of symbols and acronyms.